The aim of this research program is to understand in molecular detail the mechanism by which the replication of Herpes simplex- 1 (HSV-1) virus DNA is initiated and sustained. We propose to reconstitute in vitro with purified enzymes the orderly, semi- conservative replication of the HSV-1 genome. We expect that these studies should provide us with an insight into the mechanism by which replication of a eukaryotic genome is initiated. They should also yield information about the replication of a class of animal viruses that are of great public health importance. The investigation will be organized along the following lines: 1. Identification, purification and analysis of HSV-1 encoded replication proteins a. HSV-1 DNA polymerase b. HSV-1 single-stranded DNA binding protein (ICP8) c. HSV-1 induced replication factor(s) d. HSV-1 induced DNA helicase e. HSV-1 induced primase f. HSV-1 induced oriS binding protein g. Rolling circle DNA replication with purified proteins 2. Initiation of DNA replication at an HSV-1 origin (oriS) 3. In vitro inversion of HSV-1 L and S sequences